tanru grouping

The default grouping in Lojban is leftwards. This means that, if you have three things connected together in Lojban, the first two go together before you join in the third. For example, la djiotis. .e la suzyn. .onai la ranjit means not "Jyoti and either Susan or Ranjeet", but "Either Jyoti and Susan, or Ranjeet."

Does the distinction matter? Depends on your background; programmers, for example, are often driven to distraction in making sure their logical connectives work out in the right order (usually by copious use of brackets.) But there is often a real difference in meaning; the first interpretation given above describes a couple, for example, but the second doesn't.

The grouping of terms in Lojban grammar is particularly important when it comes to tanru. The way gismu group together in a tanru determines what that tanru means. For example,

bad music magazine

has in English two interpretations: a bad magazine about music, or a magazine about bad music. In Lojban, its equivalent

xlali zgike karni

has only the interpretation 'magazine about bad music', because the first two gismu (xlali zgike 'bad music') group together first. So it is important to be able to modify the grouping of gismu, so that we can make sure the tanru means what we actually intend it to mean. For that reason, Lojban has a couple of mechanisms in place for making tanru group together properly.

If you are a programmer, or a mathematician, you have long ago made brackets your trusted aide in dealing with this kind of problem. So you won't be surprised to hear that Lojban has cmavo that act as parentheses, grouping gismu together. Those cmavo are not to and toi: those are reserved for your own parenthetical comments, and you never know when you might want to insert a snide remark in the middle of a particularly arduous tanru. Rather, the cmavo you need are ke, to open the grouping bracket, and ke'e, to close it. So if xlali zgike karni means a {bad music} magazine, then a bad {music magazine} is in Lojban:

xlali ke zgike karni ke'e

Now, ke'e is a terminator, like all the other terminators we've seen: ku, kei, ku'o, vau, and so on. And like those terminators, it can be dropped out when no ambiguity will result. So if we know we're at the end of the tanru, having reached the end of the selbri (because we've just bumped into a sumti, say, or a new sentence), then we also know that any open ke brackets must now close; so ke'e can be omitted. This means you won't necessarily see a ke'e 'close bracket' after each ke 'open bracket':

.i mi pu zi te vecnu lo xlali ke zgike karni .i to'e zanru la'o gy. Eurythmics gy.
I just bought a bad {music magazine [}]. It dissed the Eurythmics.

That's one way of grouping together gismu in tanru. The other way is to use a cmavo we've already seen in a related role: bo. When bo appears between two gismu, it means that those gismu group together more tightly than anything else. So an alternative way of saying bad {music magazine} is

xlali zgike bo karni

This means that zgike bo karni should count as a unit, to which the description xlali 'bad' applies.

bo does the same job with sentences (.i bo, .i ba bo, .i seni'i bo all attach to only the preceding sentence), with connectives (.e bo, gi'e bo), and so on. So if I want to say "Jyoti and either Susan or Ranjeet", I would say

la djiotis. .e la suzyn. .onaibo la ranjit.

For that matter, ke can also be used with connectives (though not with sentences; they have their own kind of bracket, tu'etu'u.) So I could also say

la djiotis. .e ke la suzyn. .onai la ranjit. ke'e

— where in most cases the ke'e may be left out.

Tip: You can't start a run of sumti with ke, for reasons of Lojban grammatical pedantry we won't go into here.

Tip: An advantage of putting the connective before the two terms, or after the two terms, is that you can completely avoid this kind of ambiguity. The more geeky among you will have heard of Reverse Polish notation: this does arithmetic by placing the operators after the numbers they operate on (e.g. (2 + 3) 5 becomes 2 3 + 5 ), and so avoids having to use brackets. The same holds for Lojban forethought connectives: "Jyoti and either Susan or Ranjeet" is

ge la djiotis. gi gonai la suzyn. gi la ranjit.

and "Either Jyoti and Susan, or Ranjeet" is

gonai ge la djiotis. gi la suzyn. gi la ranjit.

Since there is no ambiguity, you won't need bo or ke with forethought connectives.

Exercise 3

Gloss the following into English, using brackets to indicate their structure. For instance:

xlali zgike karni
( ( bad music ) magazine )

  1. xlali bo zgike karni

  2. xlali zgike bo karni

  3. ke xlali zgike karni

  4. ke xlali zgike bo karni

  5. xlali ke zgike ke karni ke tcidu

  6. xlali zgike bo karni tcidu

  7. xlali zgike ke karni tcidu

  8. ke xlali zgike ke'e karni tcidu

  9. xlali ke zgike karni ke'e tcidu

  10. ke xlali zgike bo karni ke'e tcidu